Semiconductor chips are typically sealed in a package that is soldered to a printed circuit board. The various connections between the electrical components on the chip and the conductors on the printed circuit board are made through conductors that pass through the package and are connected to the printed circuit board by solder. Within the package, the chip is encapsulated in a potting compound that protects the chip from damage caused by exposure to moisture and oxygen.
Early chip designs contained relatively few active components operating at relatively slow speeds, and hence, heat dissipation was not a major problem. However, as chip speeds and component densities have increased, heat dissipation has become a major problem. One prior art method for increasing the heat dissipation in a semiconductor package utilizes a heat-conducting cover. In this design, the cover is placed over the encapsulated chip to improve the heat conduction from the chip to the air above the chip. Unfortunately, this approach is of limited value since the heat dissipating cover depends on the conduction of the heat from the chip through the encapsulating material, which is a poor heat conductor. In addition, the surface area of the cover is limited to the size of the semiconductor package, and hence, the amount of heat that can be dissipated by the cover is limited.